"Our Brand Is Crisis" straddles the line between satire and serious political drama, but its humor lacks the bite of similarly minded features like 1997's "Wag the Dog" and 1999's "Election." What it does have on its side are a pair of sharp performances from Sandra Bullock (2013's "Gravity") and Billy Bob Thornton (2015's "Entourage"), their barbed onscreen maneuvering carrying the picture through some meandering rough patches and a script by Peter Straughan (2011's "The Debt") that severely underutilizes its supporting cast.

An illustrious strategist whose nickname of "Calamity Jane" proceeds her, Jane Bodine (Sandra Bullock) is lured out of her self-imposed retirement to turn around the sagging poll numbers of erratic Bolivian presidential candidate Pedro Castillo (Joaquim de Almeida). Once she lands in the South American country and her extreme altitude sickness subsides, she gets to work on altering the angle of Castillo's campaign, playing upon the civil and socioeconomic fears of the voters—the crisis of the title—while positioning the senator as a tough, passionate leader who gets things done. Jane scarcely believes a word of what she's hawking, but that is the name of the game in her line of work. Adding fire in her belly is the hot-shot, dirty-dealing Pat Candy (Billy Bob Thornton), the adversarial political consultant working for leading opponent/candidate Victor Rivera (Louis Arcella). As Jane tells it, she and Candy have been on opposite sides for three or four elections, and he has come out on top three or four times.

Suggested by Rachel Boynton's 2006 documentary of the same name, "Our Brand Is Crisis" is compelling when it is focusing on Jane and Pat's part-composed, part-acrid sparring and the ignoble, back-door strategizing of political campaigns. If director David Gordon Green (2013's "Prince Avalanche") shortchanges his depiction of the Bolivian people, casting them to the sidelines to make way for the predominately white, North American central actors, his earnest ultimate motivations at least reveal themselves by the provocative final minutes.

An uncompromised Sandra Bullock is the appealing focus, playing a progressive, complicated female character who is defined by her intelligence and professional proficiency rather than her gender or the men in her life. Her Jane Bodine is a blazing force with years of experience behind her, unafraid to speak her mind no matter the circumstance. She also, intriguingly, is not entirely mentally stable, a recovering alcoholic with an addictive personality and years of guilt on her shoulders. One suspects Jane originally fled her job for a quiet life in the mountains because she could no longer deal with making a living fighting for people she didn't believe in. Now that she has returned to this unsavory field, her unresolved emotions from the past come bubbling once more to the surface. Bullock is in total command throughout, bringing gravitas and precise comic timing to the role.

As the fantastically named Pat Candy, Billy Bob Thornton is entertainingly spiteful and unruffled to a fault, popping up to give the proceedings a jolt of energy every time the pacing begins to lag. The rest of the actors are given little to do, an observation made increasingly obvious as Anthony Mackie (2014's "Captain America: The Winter Soldier"), Ann Dowd (2012's "Compliance"), Scoot McNairy (2014's "Gone Girl") and Zoe Kazan (2012's "Ruby Sparks") stand around for the duration as part of Jane's team, patiently waiting for their too-rare moments in the spotlight. As untrustworthy Presidential hopeful Pedro Castillo, Joaquim de Almeida (2011's "Fast Five") is memorable enough to wish his character was more clearly explored. As is, it is tough to get a handle on who he is and what he stands for. Then again, maybe that is the point.

"If voting changed anything, they'd make it illegal," Jane says near the end of "Our Brand Is Crisis." Her words may sting with cynicism, but she has been around the block enough times to know her statement is also true. Her decision to no longer be a part of the problem gives the film a potent human arc and a stimulating thematic consciousness just as the story's race to election day has grown stale and repetitive. "Our Brand Is Crisis" is too soft in its foundation to make the splash it hopes for, but Sandra Bullock's assertive, adeptly shaded turn proves eminently watchable.